Investigation of membrane complexes of myelin and gregarine pellicle by freeze-drying and freeze-etching methods.
By the changes introduced in the standard procedures of the freeze-drying method (fixation, transportation of specimens from a vacuum apparatus into glass capillary tubes, and embedding) we have managed to simplify the method and to increase the reliability of the results. Fixation of the tissue was carried out after freeze-drying in molecular beams of OsO4 or in an OsO4 solution in carbon tetrachloride. The samples were embedded in araldite through mixtures of carbon tetrachloride and araldite. Membranes of myelin and gregarine pellicle were investigated. The repeat period of myelin at fixation of nerves after freeze-drying in OsO4 molecular beams is 11.2 +/- 0.5 nm and in an OsO4 solution in carbon tetrachloride, 12 +/- 0.4 nm. A tetragonal reticulum was revealed on the plasma-membrane extracellular surface of gregarine which had been prepared by freeze-drying. This type of structure is never observed after the routine fixation in water, while an analogous structure is revealed after freeze-etching.
D000818:Animals; D002462:Cell Membrane / Q000648:ultrastructure; D056890:Eukaryota / Q000648:ultrastructure*; D005612:Freeze Drying / Q000295:instrumentation / Q000379:methods; D005613:Freeze Etching / Q000379:methods; D008854:Microscopy, Electron / Q000379:methods; D009186:Myelin Sheath / Q000648:ultrastructure*; D011896:Rana temporaria; D012584:Sciatic Nerve / Q000648:ultrastructure